1. Field of the Invention
The present invention provides an extraction device capable of capturing and releasing hard objects, and particularly for surgically moving, manipulating and extracting biological material and man-made material from the human body, such as required in ureteroscopic and renal stone extraction procedures.
2. Description of the Prior Art
Various instruments are known in the art for surgically removing stones and other hard materials from the body. An example is an instrument disclosed in U.S. Pat. No. 5,944,728 to Bates, which is incorporated herein by reference. Bates"" instrument has arcuate legs that form a basket when a plunger is in a distal position, allowing the legs to radially collapse toward each other. The legs are actuated independently of the plunger with a cable, and may have cross-sectional shapes such as rectangular, round, D-shaped, or V-shaped. To expand the legs, the plunger must be actuated into engagement with the legs, forcing the legs radially apart from each other. As such, surgically moving, manipulating and extracting material from the human body is complicated by the requirement to additionally operate the plunger to expand and contract the legs.
The present invention provides an extraction device that comprises a sheath, distal legs that project from the sheath, and actuating means for retracting the legs into the sheath and deploying the distal legs from the sheath. The distal legs are formed to have a parabolic curved shape, such that the distal legs automatically deploy radially outward and away from each other when deployed outside the sheath with the actuating means. As such, a plunger is not required to operate the legs. When retracted into the sheath with the actuating means, the distal legs elastically deform, collapsing radially toward each other to acquire a mid-deployed position in which the legs define a basket. The legs can be further retracted into the sheath, providing a stowed position in which the legs are elastically deformed to be substantially parallel to each other.
According to the invention, each of the distal legs has a concave cross-section that contributes greater strength to the legs while providing sufficient resiliency, such that the legs are able to maintain their form and alignment and provide greater grasping strength and expansion force than extraction devices of the prior art, while eliminating the requirement for a plunger or another additional component. As a result, the device is not only capable of moving, manipulating and extracting biological material, such as calculi and stones, but also man-made material such as implants and stents. The distal ends of the legs define jaws that are preferably angled outward so that an embedded material can be more readily extracted, such as a stone from the wall of the calyces in a kidney. An additional preferred feature of the invention is that the sheath is hollow to allow passage of irrigant or a laser fiber used to disintegrate biological materials. The sheath also may also include a hollow channel through which a sparking wire can be passed to enable the legs (if formed of a conductive material) to be energized with electrosurgical cutting or coagulating current.
Other objects and advantages of this invention will be better appreciated from the following detailed description.